flutter_blue 蓝牙插件实战及那些坑

Posted 2021-03-15 ljx20180807

项目场景： 地下车库无网路的情况下需要使用蓝牙对小区门禁进行开门 

本人掘金文章

坑一： 安卓端引入flutter_blue运行项目报错

1. 原因： 安卓sdk版本需要28以上

2. 解决： android/build.gradle 下修改 compileSdkVersion  targetSdkVersion 为 28；  minSdkVersion 修改为19

android {
.............
    compileSdkVersion 28
.............
    defaultConfig {
        minSdkVersion 19
        targetSdkVersion 28
    }
.............
}

坑二： ios引入flutter_blue运行项目报错

1. 原因： windows 创建的 flutter swift 语言, 而ios要的是 objc

2. 解决： 新建空目录使用 flutter create -i objc my-flutter-app 创建新项目， 在把原项目下lib文件夹下的所有文件替换新创建的lib文件夹， 这就可以了；Androidios 端都没问题

附上实际项目的源码; 其他的坑暂时就没想起来了，反正坑蛮多，初期运行时也是控制台各种报错

需求简介：

1. 执行完一次蓝牙开门之后，就断开连接蓝牙，以降低手机耗能；
2. 20s扫码一次蓝牙，扫描时长为10s,以便根据距离搜索新的及强度高的蓝牙设备
3. 初始化项目即执行一次蓝牙扫描

import ‘package:flutter_blue/flutter_blue.dart‘;
FlutterBlue flutterBlue = FlutterBlue.instance;
# // 蓝牙开门
void _blueOpenDoor (Map list) async {
var isFirstScan = true;
var isConnect = false;
_delayed?.cancel();
# // 自定义loading
cancel = BotToast.showCustomLoading(
  ignoreContentClick: true,
  toastBuilder: (cancelFunc) {
    return Loading();
  }
);
blueList.forEach((scanResult) async {
  # // if (scanResult.device.name == ‘201901012212‘) {
  if (scanResult.device.name == list["macAddress"]) {
    print(‘蓝牙设备门禁正在连接~~~~~~~~~‘);
    await scanResult.device.disconnect();
    await scanResult.device.connect();
    isConnect = true;
    print(‘蓝牙设备门禁连接成功~~~~~~~~~‘);
    # // List<BluetoothDevice> connectedDevices = await flutterBlue.connectedDevices;
    // if(connectedDevices.contains(scanResult.device)) {
    //   // TO DO
    // }
    List<BluetoothService> services = await scanResult.device.discoverServices();
    # //遍历蓝牙设备对列表
    services.forEach((service) async {
      if (service.uuid.toString().toUpperCase().substring(4, 8) == ‘FFF0‘) {
        var characteristics = service.characteristics;
        for(BluetoothCharacteristic c in characteristics) {
          if (c.uuid.toString().toUpperCase().substring(4, 8) == ‘FFF1‘) {
            # // 开门指令
            print(‘蓝牙设备门禁服务匹配成功~~~~~~~~~‘);
            await c.write([0x30, 0x10, 0x02, 0x03 ...........]);
            print(‘蓝牙设备门禁指令发送成功~~~~~~~~~‘);
            # // 开门声音
            cancel();
            _delayed?.cancel();
            showOpenDoorDialog(1, list[‘doorControlName‘]);
            await _audioPlayer.play("https://qinlin-resource.oss-cn-zhangjiakou.aliyuncs.com/wechat/opendoor.mp3");
            await scanResult.device.disconnect();
          }
           # // 监听门禁返回 并断开连接
           if (c.uuid.toString().toUpperCase().substring(4, 8) == ‘FFF2‘) {
             # // List<int> value = await c.read();
             # // print(‘88888888888888888888888$value‘);
             await c.setNotifyValue(true);
             notifySubscription = c.value.listen((value) async {
               print(‘88888888888888888888888$value‘);
               cancel();
               await scanResult.device.disconnect();
               notifySubscription.cancel();
             });
           }
        }
      }
    });
    # // 获取设备连接状态
    stateSubscription = scanResult.device.state.listen((s) async {
      print(‘连接状态连接状态$s‘);
      switch (s) {
        # // 蓝牙连接成功
        case BluetoothDeviceState.connected:
          isFirstScan = true;
          break;
        case BluetoothDeviceState.disconnected:
          if (!isFirstScan){
            cancel();
            _delayed?.cancel();
            print(‘蓝牙设备门禁连接失败~~~~~~~~~‘);
            BotToast.showText(
              text: ‘蓝牙设备连接失败，请稍后再试‘, 
              align: Alignment(0, 0.1),
              onlyOne: true, 
              duration: Duration(milliseconds: 2000),
              contentPadding: const EdgeInsets.all(15.0),
            ); 
          }
          break;
        default:
          cancel();
          _delayed?.cancel();
          print(‘蓝牙设备门禁连接失败~~~~~~~~~‘);
          BotToast.showText(
            text: ‘蓝牙设备连接失败，请稍后再试‘, 
            align: Alignment(0, 0.1),
            onlyOne: true, 
            duration: Duration(milliseconds: 2000),
            contentPadding: const EdgeInsets.all(15.0),
          ); 
          break;
      }
    });
  }
});
_delayed = Timer.periodic(new Duration(seconds: 15), (timer) {
  cancel();
  if (!isConnect) {
    BotToast.showText(
      text: ‘该门禁蓝牙信号较弱，请稍后再试‘, 
      align: Alignment(0, 0.1),
      onlyOne: true, 
      duration: Duration(milliseconds: 2000),
      contentPadding: const EdgeInsets.all(15.0),
    ); 
  }
  _delayed?.cancel();
});

}
# // 15s 定时扫描蓝牙
Future<dynamic> _scanBlue () async {
flutterBlue.state.listen((s) {
  if (s == BluetoothState.on) {
    setState(() {
      _isOpenBlue = true;
    });
    FlutterBlue.instance.stopScan();
    # // 立即执行一次
    _initScan();
    _timer = Timer.periodic(new Duration(seconds: 20), (timer) {
      setState(() {
        blueList = [];
      });
      scanSubscription = flutterBlue.scan().listen((scanResult) async {
        if (!blueList.contains(scanResult)) {
          setState(() {
            blueList.add(scanResult);
          });
        }
      });
      Future.delayed(Duration(seconds: 10), () {
        FlutterBlue.instance.stopScan();
        scanSubscription?.cancel();
      });
    });
  } else {
    _timer?.cancel();
    if (!_isOpenBlue) {
      final snackBar = new SnackBar(
        content: new Text(‘如需要蓝牙开门，请先前往手机设置开启蓝牙‘),
        backgroundColor: Colors.red,
        duration: Duration(seconds: 3),
        action: SnackBarAction(
          textColor: Colors.white,
          label: ‘关闭‘,
          onPressed: () {},
        ),
      );
      _scaffoldkey.currentState.showSnackBar(snackBar);
    }
  }
});
}
# // 初始执行扫描
void _initScan () {
setState(() {
  blueList = [];
});
scanSubscription = flutterBlue.scan().listen((scanResult) async {
  if (!blueList.contains(scanResult)) {
    setState(() {
      blueList.add(scanResult);
    });
  }
});
Future.delayed(Duration(seconds: 10), () {
  FlutterBlue.instance.stopScan();
  scanSubscription?.cancel();
});
}

有问题欢迎留言